Research On In-wheel Motor Multi-physics Coupling Characteristics And Cooling Of Distributed Drive Electric Vehicle

Under the guidance of the goals of "carbon peaking" and "carbon neutrality",my country’s economic and social development is undergoing a comprehensive green transformation.New energy vehicles represented by pure electric vehicles will undoubtedly become the mainstream of the future automobile market.In-wheel motor distributed drive electric vehicles have significant advantages over traditional fuel vehicles and mainstream new energy vehicles,and the combination of in-wheel motor drive technology and pure electric vehicles will bring about disruptive changes in automotive technology.In this context,the research on multi-physics coupling characteristics of in-wheel motors for distributed drive vehicles has become a hot topic.This paper takes the in-wheel motor of electric vehicle as the research object,and builds a multi-physics coupling model integrating mechanics,electricity,magnetism,and heat based on the bond graph theory,and combines different simulation methods to analyze the motor under the action of multi-physics coupling.The characteristics are deeply explored to provide theoretical reference for the design and improvement of the in-wheel motor.The main research contents of the paper are as follows:(1)Determining the main parameters of in-wheel motor for distributed drive pure electric vehicle.Through the comparison of different types of motors,the permanent magnet synchronous motor(PMSM)with the best comprehensive performance is selected as the drive motor.According to the vehicle parameters of the target model and the vehicle power index,the parameter matching calculation and temperature rise analysis of the in-wheel motor are carried out,the cooling system of the in-wheel motor is designed,and the three-dimensional model of the distributed drive vehicle and the in-wheel motor angle module system is established.The control principle of the in-wheel motor is briefly introduced.(2)The multiphysics coupling model of the in-wheel motor is constructed based on the bond graph theory.By analyzing the working process and energy transfer path of the in-wheel motor,the corresponding physical model is established,and then the bond graph model of the in-wheel motor electromechanical system and the cooling system is established according to the bond graph modeling rules.Finally,the two A multi-physics coupling model of in-wheel motor based on bond graph theory is constructed.(3)The multi-physics coupling characteristics of the in-wheel motor are simulated and analyzed by MATLAB/Simulink.According to the bond graph model of the in-wheel motor,the mathematical model and MATLAB/Simulink simulation model of the in-wheel motor are established.The simulation analysis is carried out for different driving conditions of the car,and the characteristic images of motor torque and temperature rise under the action of multi-physics coupling of the in-wheel motor are obtained.The simulation results show the validity of the in-wheel motor coupling model established in this paper based on the bond graph theory;at the same time,it is shown that under the same coolant flow rate,increasing the water channel section can achieve better cooling effect.With the increase of the coolant flow rate,the cooling rate of the cooling system gradually decreases,and finally becomes stable.Based on the above work,this paper uses Fluent to simulate the surface wind speed of the in-wheel motor under the natural driving state of the car and the motor temperature under different cooling methods.By setting different cooling conditions,the cooling water channel structure and the cooling liquid flow rate are compared and analyzed.The influence of temperature characteristics verifies the above conclusion.